Case Environmental
Case Environmental

Chlorination Certificates & Disinfection

Disinfection/chlorination of premises following Covid Lockdowns

UK Government guidance is to treat plumbing systems that have been out of regular use (and not flushed weekly or where the control regime has not been effective) as a new system and chlorinate prior to using.  The requirement for chlorination can be as little as two weeks out-of-use and as such many business and educational premises may require this service following lockdown when reopening.  It is recommended that this is carried out a week before the buildings are in use again.


Why Case Environmental?  We provide specialist chlorination/sterilisation/disinfection and UKAS testing nationwide.  Our staff hold EUSR National Water Hygiene Cards and are  WIAPS registered.  For further information or a quote please email or complete the form below.


Chlorination certificate  Disinfection by chlorination is a common contract requirement for new internal plumbing prior to handover.  A chlorination certificate may also be needed for new 'over-sized' external water pipes prior to a new water connection; before connection to mains pipe work the water company will need to see a chlorination certificate (to British Standards BS6700, BS EN 806 or BS8558) and if needed, the sample results of a UKAS certified microbiology test.  For many sites a chlorination certificate can be provided same day.


The Chlorination process

  1. Flush/swab pipe work/tank/reservoir with mains water.  Record background chlorine residual.
  2. Introduce 50ppm (mg/l) chlorine solution.
  3. Allow 50ppm chlorine to sit in contact for 1 hour.
  4. Flush pipe work until start chlorine level is reached, de-chlorinating water as necessary.  Test & record onsite parameters.
  5. If collecting a UKAS microbiological sample, wait 30 minutes prior to sample collection.


Chlorination equipment  Precise chlorine dosing equipment is used to add the correct chlorine residual throughout the length of the pipework.  Onsite chlorine levels are electronically measured using a photometer and microbiological samples are tested in an UKAS laboratory.  Materials, products and chemicals used are approved for use in contact with drinking water.  This includes ultra low bromate sodium hypochlorite.


Why is chlorination required?  Chlorination ensures that the pipe work is hygienic and the water is free from contamination.  Chlorination is important for newly installed pipework, existing plumbing systems or where contamination is suspected. 


Last Minute/Same Day/Emergency Chlorination Certificate?  If you need a last minute, same day chlorination certificate, please give us a call to see if we can help.


Chlorination after prolonged period of non-use  The HSE document; Legionnaires’ disease Part 2: The control of legionella bacteria in hot and cold water systems details the actions to take when recommissioning plumbing systems taken out-of-use (and not regularly flushed).  Paragraph 2.52 on page 24 states that prior to ue the system should be treated as a new installation and cleaned, flushed and disinfected;


As well as commercial buildings, disinfection by chlorination should be considered for domestic properties such as those that have been unoccupied for a prolonged period prior to new owners/tenants.


Chlorination/disinfection/sterilisation/flushing services can also be provided for the following;

  • Tank chlorination
  • Office, Shop, restaurant and cafe shopfitting chlorination
  • Rental properties chlorination
  • Hotel & holiday park chlorination
  • Chlorination of new build properties 
  • New mains chlorination
  • Emergency chlorination
  • Commissioning of new buildings chlorination (frequent contract requirement)
  • Private water to mains conversions chlorination
  • After bacterial contamination
  • Legionella - disinfection to HSE ACOP L8 (Legionnaires' disease. The control of legionella bacteria in water systems)
  • Water system hygiene management and systems not in regular use or flushed
  • Annual or routine system maintenance

Water company chlorination requirements and guidance - these are subject to change and are not the same across the UK water industry;

Chlorination Test Certificate

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Locations covered by Case Environmental include (but are not limited to);


Bedfordshire, Berkshire, Bristol, Buckinghamshire, Cambridgeshire, Cheshire, City of London, Cornwall, Cumbria, Derbyshire, Devon, Dorset, County Durham, East Riding of Yorkshire, East Sussex, Essex, Gloucestershire, Greater London, Greater Manchester, Hampshire, Herefordshire, Hertfordshire, Isle of Wight, Kent, Lancashire, Leicestershire, Lincolnshire, Merseyside, Norfolk, North Yorkshire, Northamptonshire, Northumberland, Nottinghamshire, Oxfordshire, Rutland, Shropshire, Somerset, South Yorkshire, Staffordshire, Suffolk, Surrey, Tyne and Wear, Warwickshire, West Midlands, West Sussex, West Yorkshire, Wiltshire, Worcestershire, Bath, Birmingham, Bradford, Brighton & Hove, Bristol, Carlisle, Cambridge, Canterbury, Chester, Chichester, Coventry, Derby, Durham, Ely, Exeter, Gloucester, Hereford, Kingston-upon-Hull, Lancaster, Leeds, Leicester, Lichfield, Lincoln, Liverpool, London, Manchester, Newcastle-upon-Tyne, Norwich, Nottingham, Oxford, Peterborough, Plymouth, Portsmouth, Preston, Ripon, Salford, Salisbury, Sheffield, Southampton, St Albans, Stoke-on-Trent, Sunderland, Truro, Wakefield, Wells, Westminster, Winchester, Wolverhampton, Worcester and York.



Blaenau Gwent, Bridgend, Caerphilly, Cardiff, Carmarthenshire, Ceredigion, Conwy, Denbighshire, Flintshire, Gwynedd, Isle of Anglesey, Merthyr Tydfil, Monmouthshire, Neath Port Talbot, Newport, Pembrokeshire, Powys, Rhondda Cynon Taff, Swansea, Torfaen, Vale of Glamorgan, Wrexham, Bangor, Cardiff, Newport, St Davids and Swansea.



Ayrshire, Dumfries and Galloway, Edinburgh and The Lothians, Glasgow and Clyde Valley and The Borders.


London Boroughs

Barking and Dagenham, Barnet, Bexley, Brent, Bromley, Camden, City of London, Croydon, Ealing, Enfield, Greenwich, Hackney, Hammersmith and Fulham, Haringey, Harrow, Havering, Hillingdon, Hounslow, Islington, Kensington and Chelsea, Kingston upon Thames, Lambeth, Lewisham, Merton, Newham, Redbridge, Richmond upon Thames, Southwark, Sutton, Tower Hamlets, Waltham Forest, Wandsworth and Westminster.


Water Companies

Affinity Water, Albion Water, Anglian Water, Bournemouth Water, Bristol Water, Cambridge Water Company, Cholderton and District Water Company, Dee Valley Water, Dŵr Cymru Welsh Water, Essex and Suffolk Water, Hartlepool Water, Northumbrian Water, Portsmouth Water, Severn Trent Water, South East Water, Southern Water, South Staffordshire Water, South West Water, Sutton and East Surrey Water, Thames Water, United Utilities, Wessex Water, Yorkshire Water and Youlgrave Waterworks.

Example Chlorination/Disinfection Certificate PDF
Example Chlorination Certificate.pdf
Adobe Acrobat document [270.8 KB]
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